The present invention relates to a method and an apparatus for determining temperatures and flow rates of urine during micturition and for determining other variables, and for obtaining a urine sample for clinical laboratory analysis.
Measurement of urinary flow rates (uroflowmetry) during micturition is an important technique of evaluating lower urinary tract dysfunction. Average flow rates and the peak flow rate, along with the patterns of changing flow rates during the micturition event allow physicians to identify conditions of outflow obstruction and differentiate between anatomic and neurologic disease.
The simplest form of uroflowmetry is observation of the urine stream by a trained physician. A simple and more quantifying technique is timing the voiding of a patient while collecting the urine into a calibrated container, thereby allowing average flow rate to be calculated. Other devices allow peak flow rate to be estimated by collecting urine into chambers of varying sizes in a device, with the filling of the chambers dependent upon flow rates. Observation of urination, however, is embarrassing to many patients, and many cannot void or do not void normally under such conditions. Furthermore, observation, timed voiding, and peak flow measurement alone give only partial information about how the patient urinates.
Electro-mechanical devices have been devised to make a recording of urine flow rates during micturition. Many technologies have been used to make the measurement. Measurement by weight is a common technique. Weight represents volume, and change in weight over time represents flow rate. Other technologies include micro-turbines in which the urine flowing through a tube acts upon a small fan blade, the rotation of which is proportional to urine flow rate, with the rotation being measured optically. Another technique employs a DC motor with a blade rotating at a fixed speed. The urine acts upon the blade to impede its rotation causing the motor to draw more current to rotate the blade at a fixed speed. The change in current draw is then measured and reflects flow rate. Other techniques reported include measurement of the electrolytic properties of urine, measurement of the cooling effect of the flow of urine on a heated electrode, and occlusion of a CO.sub.2 valve by the urine stream. Further, in the past a capacitor has been used to measure volume in a cylinder with change in volume representing flow rate. However, such a device has not been acceptable in practice because of the errors which result in certain portions of the data generated.
With the exception of the weight transducer method, all the other techniques require the urine to come into contact with the sensor mechanism. This has several shortcomings. First, the sensors must endure repeated exposure to urine, which is corrosive and damaging to the sensors. Cleaning is of utmost importance to maintain reliable performance of the sensor. Cleaning is also important in that infected urine may remain in or on the mechanism, allowing bacteria to grow and exposing other patients to disease. Further, since urine from several patients comes into contact with the sensor mechanism, the urine cannot be used reliably for clinical chemical and microbiological analysis. On a practical basis, the sensor systems cannot be cleaned adequately to provide the level of cleanliness required for such urinalysis.
While the urine does not directly contact weight-type sensors, similar problems exist. Urine is collected into a vessel which rests on the weight sensor. The sensor must be isolated from patient contact, and the urine must be directed into the collector from a standard size and height channel such that the weight measurement is not changed by the kinetic forces of the urine stream. Therefore a weight-type apparatus must provide a means of directing the urine into the collection cup. Since urine contacts this portion of the apparatus (generally a large funnel), this system obviates the use of the voided urine for additional laboratory tests.
Patients requiring both urinalysis test and urine flow rate measurement now must void twice during the visit to the physician's office or clinic. This presents a practical problem, and in some cases patients try to hydrate quickly by drinking excessive amounts of fluid. This can lead to short-term metabolic imbalances which can distort the results of urinalysis. Many patients requiring the urine flow test also require urinalysis. Obstruction and infection are frequently concurrent and may have causal relationships. Outflow obstruction can cause high pressure in the bladder during micturition resulting in reflux of urine into the kidneys. This may result in impaired kidney function which is measured through chemical urinalysis.
Current alternatives to direct witnessing include: (1) temperature measurement of the sample after voiding as a test of whether it was freshly voided; (2) aural witnessing by an individual outside a commode stall or bathroom; (3) chemical analysis of the urine for pH and other characteristics; (4) requiring the subject to undress before entering the bathroom; (5) removal of faucets from the bathroom so the subject cannot dilute the sample with water; and (6) putting bluing agents in the toilet to prevent dilution with toilet water. None of these approaches is entirely satisfactory, however, and there is therefore a need for a system which eliminates such complicated, labor-intensive and unreliable steps.
Employment related and forensic drug testing of urine samples has increased greatly in recent years. However, a certain amount of fraud has occurred in the provision of samples. Organizations requiring the tests feel that in many instances the validity of the testing programs has been compromised. In order to ensure that samples are genuine and unadulterated, direct witnessing of the subject's urination is often required. This requirement causes a great deal of humiliation and embarrassment for many subjects. In addition, much of the collection is done in industrial medical clinics or other health-care institutions where the professional medical staff members are asked to witness the urination. Many find this inconsistent with their training, professional objectives and personal standards. Therefore, there is a need for an alternative to human witnessing as a means for ensuring that urine sample was freshly voided by the subject.
There is also a need for a system which provides a consistent, objective technique for collecting the sample, and for ensuring its validity. Protocols for ensuring authenticity vary from collection site to collection site, and may vary from shift to shift at a single collection site, because of the unwillingness of staff members to watch urination. In addition, any action taken with an individual being tested which even implies an attempt to provide a fraudulent sample may expose a testing agency to liability for uneven or unfair treatment. There is thus a need for a testing program with an automated, objective collection witnessing protocol, in order to reduce the potential for human error and uneven treatment.